Research And Application Of Bending Properties Of Composite Metal Foam And Sandwich Structure

With the rapid development of economy,the domestic per capita disposable income is increasing.As a convenient means of transportation,cars have entered thousands of households.With the increase of car ownership in China,road traffic accidents occur frequently,which makes people put forward higher requirements for the safety of cars.Materials and structures with excellent energy absorption and cushioning properties have great application prospects in automotive collision avoidance design,including foam materials and sandwich structures.Composite metal foam attracts much attention due to its high energy absorption and strong design.In this paper,the mesoscopic and macroscopic models are used to simulate the bending performance of the composite metal foam and its sandwich structure,and the sandwich structure is applied to the anti-collision system of the vehicle body,which improves the crashworthiness of the vehicle body.Firstly,on the basis of the typical sphere random packing algorithm,the idea of layering and reordering compression is proposed,and the algorithm is optimized by programming software.The results show that the optimized algorithm improves the packing density of the limit sphere,and establishes the random model under different geometric parameters.It lays the foundation for subsequent numerical simulation to study the bending properties of the composite metal foam meso model.Secondly,the composite metal foam was prepared by casting method,and the sample was cut.The 3-point bending experiments were carried out on several samples.The results of analysis and comparison showed that the thickness of the sample containing at least the whole hollow sphere better represented the bending property of the composite metal foam.Through the reduction of the microscopic model of the sample to the experimental results of the bending performance of the composite metal foam in the standard experiment,the research shows that the weak matrix of the material is liable to fracture,resulting in the decrease of the bearing capacity.The effect of geometric parameters on the bending properties of composite metal foam was studied.The results showed that the bending resistance of composite metal foam first decreased and then increased with the increasing number of hollow spheres.With the increase of the thickness of hollow spheres,the flexural properties of composite metal foam also increase,but the extent of increase is smaller.Thirdly,the macro model is used to simulate the bending performance of the composite metal foam sandwich structure,and the effect of the thickness of the panel and the thickness of the core layer on the bending performance of the sandwich structure is studied.The results show that the flexural performance of the sandwich structure will be enhanced with the increase of the panel thickness when the panel thickness is small,but due to the failure of the core layer,the extent of enhancement gradually becomes smaller.In addition,although the increase of core thickness is beneficial to improve the bearing capacity,the improvement of flexural performance is limited due to the increase of flexural section coefficient of the whole sandwich structure.Finally,the composite metal foam sandwich structure is applied to the body collision avoidance system of a vehicle.The deformation and energy absorption of the anti-collision system under impact load are simulated and analyzed.The results show that the composite metal foam sandwich structure can effectively improve crashworthiness of car body collision avoidance system.